College

The quotient of [tex]$\left(x^4+5x^3-3x-15\right)$[/tex] and [tex]$\left(x^3-3\right)$[/tex] is a polynomial. What is the quotient?

A. [tex]$x^7+5x^6-6x^4-30x^3+9x+45$[/tex]

B. [tex]$x-5$[/tex]

C. [tex]$x+5$[/tex]

D. [tex]$x^7+5x^6+6x^4+30x^3+9x+45$[/tex]

Answer :

To find the quotient of the polynomial division, let's start by reviewing the given problem:

We have two polynomials:
- Dividend: [tex]\(x^4 + 5x^3 - 3x - 15\)[/tex]
- Divisor: [tex]\(x^3 - 3\)[/tex]

We need to divide the dividend by the divisor to find the quotient. The division will result in a quotient and possibly a remainder, but we're focused on finding the quotient here.

Here’s a step-by-step explanation of how polynomial long division works in this case:

1. Divide the leading term of the dividend by the leading term of the divisor:

Divide [tex]\(x^4\)[/tex] (the leading term of the dividend) by [tex]\(x^3\)[/tex] (the leading term of the divisor). This gives us [tex]\(x\)[/tex].

2. Multiply the entire divisor by this result:

Multiply [tex]\(x^3 - 3\)[/tex] by [tex]\(x\)[/tex], resulting in [tex]\(x^4 - 3x\)[/tex].

3. Subtract this result from the original dividend:

Subtract [tex]\(x^4 - 3x\)[/tex] from [tex]\(x^4 + 5x^3 - 3x - 15\)[/tex]. This subtraction leaves you with:
[tex]\[
(x^4 + 5x^3 - 3x - 15) - (x^4 - 3x) = 5x^3 + 0x^2 + 0x - 15
\][/tex]
Which simplifies to:
[tex]\[
5x^3 - 15
\][/tex]

4. Repeat the division process for the new polynomial:

Divide the new leading term [tex]\(5x^3\)[/tex] by [tex]\(x^3\)[/tex], which gives us [tex]\(5\)[/tex].

5. Multiply the divisor by this new result:

Multiply [tex]\(x^3 - 3\)[/tex] by [tex]\(5\)[/tex], which results in [tex]\(5x^3 - 15\)[/tex].

6. Subtract this from the current polynomial:

Subtract [tex]\(5x^3 - 15\)[/tex] from [tex]\(5x^3 - 15\)[/tex]:
[tex]\[
(5x^3 - 15) - (5x^3 - 15) = 0
\][/tex]
Since there is nothing left over, it shows that the remainder is 0.

The quotient from this division is:
- [tex]\(x + 5\)[/tex]

This process confirms that our solution to the division is [tex]\(x + 5\)[/tex], and since there's no remainder, the quotient is indeed a complete representation of the division of these polynomials.